1. Field of the Invention
This invention relates to a process for synthesizing 2-vinyl-4,6-diamino-s-trazine (to be abbreviated as VT).
2. Description of the Prior Art
VT is a compound represented by the following structural formula, and has vinyl-polymerizability. ##STR1##
VT has a melting point of 239.degree. to 241.degree. C., and is soluble in hot water but sparingly soluble in hot methanol, hot ethanol and hot acetone. It is almost neutral. When VT is dissolved in hot water and azobisisobutyronitrile is added, a polymer insoluble in hot water is formed.
TLC (alumina and silica, EtOH): Rf=0.0
.nu..sub.cm.spsb.-1.sup.KBr : 3340, 3170, 1680 (4th absorption), 1655 (2nd absorption), 1550 (1st absorption), 1460 (5th absorption), 1425 (3rd absorption), 1370, 1265, 1130, 985, 960, 835 (6th absorption).
NMR (d.sub.6 -DMSO): .delta. 6.76 (m, 4H), 6.35-6.45 (t, 2H), 5.59-5.72 (q, 1H).
Elementary analysis: C 44.28%, H 5.07%, N 50.02%.
VT is useful as a comonomer. It is known that when diamino-s-triazine-group is introduced into a side chain of a polymer, the softening point and glass transition point of the polymer become much higher than the original polymer, its specific gravity also increases, and its solubility changes remarkably (see, for example, Seo and Kakurai: Collection of Papers on Polymers (the Japanese-language publication), 32, 308 (1975); T. Seo, K. Abe, H. Honma, T. Kakurai: Polym. Prepn., 20, 661 (1979)).
Various methods have already been known for the synthesis of VT. They include, for example, the reaction of biguanide with acryloyl chloride (C. G. Overberger et al.: J. A. C. S., 80, 988 (1958)), the reaction of dicyandiamide with .beta.-dimethylamino-propionitrile (Hoechst, French Pat. No. 1,563,255 (1967)), the heating of 1,2-di(4',6'-diamino-s-striazinyl-(2)')-cyclobutane to 320.degree. C. under reduced pressure (Asahi Chemical Industry, Co., Ltd.: Japanese Patent Publication No. 35068/1971), and the heating of 2-.beta.-methoxyethyl-4,6-diamino-s-triazine to 350.degree. C. in a stream of nitrogen (Suddeutsche Kalkstickstoff Werke A.G.: German OLS No. 2,135,881 (1973)).
None of these prior methods for the synthesis of VT, however, lend themselves to industrial-scale practice for one or more reasons. For example, the starting materials are expensive, the reaction operation is complex, or the yield of VT is low.